The present invention relates to methods of determining radiation dosages by the evaluation of foil exposed to radiation. More specifically, the present invention relates to etching of the foil subsequent to exposure.
Various methods exist for the evaluation of foils irradiated by nuclear radiation. One common method determines radiation dosage by evaluation of nuclear tracks in an irradiated foil of track recording material through the use of subsequent chemical etching of the tracks. A second method relies upon electrochemical etching of the tracks in a cell which is subdivided into two chambers by the foil provided with the nuclear tracks, with the irradiated side of the foil being contacted by a mixture of an etchant and a solvent and the other side by an electrolyte and an electrode being immersed into each one of the liquids. An alternating voltage is applied to the two electrodes for etching the nuclear tracks so as to enlarge them by selective exposure to the attack of the mixture of etchant and solvent for a given period of time. The first conventional etching method is described in detail by Robert L. Fleischer et al in "Nuclear Tracks in Solids", University of California Press, 1975, pages 50 et seq., and a known electrochemical etching method in Bericht KfK-3805 [KfK Report No. 3805], September 1985, by Kernforschungszentrum Karlsruhe, Federal Republic of Germany, particularly pages 22 to 32.
After the tracks have been etched, the tracks are optically counted. The evaluation of the exposure is based on the optical track count.
It is a disadvantage of the methods taught in the prior art that the evaluation of irradiated foils requires two time consuming steps, namely the etching (nuclear track enlargement) and the subsequent optical counting of the nuclear tracks.